Marvin's brother had returned from Vietnam in after serving 3 years and Marvin was feeling disillusioned at Motown. It was a singles factory but rarely had great albums.
It is said Gaye conceived "What's Going On" to be from the point of view of his brother
Gaye wanted to release "What's Going On" as a single but Motown head Berry Gordy had refused-deeming it noncommercial. So Marvin refused to record until "What's Going On" was released.It was released in Jauray 1971 and went Top 5 Pop.
The rest of the album was recorded over about ten days.
If you want to know about the greatness of The Motown backing band, "The Funk Bothers", listen to the album "What's Going On" or see "Standing in The Shadows of Motown"

"What's Going On" where art meets commerce to produce a masterpiece.
and for what it's worth, I will always love this-the best version I have ever heard of The American National Anthem. Done at the 1984 NBA All Star Game.